\\[-1.8ex] Soil Heterogeneity & $-$0.755$^{**}$ & $-$0.176 & $-$0.328$^{*}$ & $-$0.271 & $-$0.142 & $-$0.054 \\ 
  & (0.344) & (0.174) & (0.172) & (0.174) & (0.163) & (0.154) \\ 
\\[-1.8ex] 
Observations & 3,107 & 3,107 & 3,107 & 3,107 & 3,107 & 3,088 \\ 
R$^{2}$ & 0.007 & 0.450 & 0.481 & 0.489 & 0.514 & 0.520 \\ 
